The present invention relates generally to magnetic resonance imaging (MRI) systems and specifically to support structures of a magnetic resonance imaging system.
MRI systems are widely used in medical community as a diagnostic tool for imaging tissue and organ structures in a subject. MRI systems establish a primary magnetic field, and a series of gradient fields that influence gyro magnetic materials in the subject to be imaged. During imaging, gradient fields are pulsed in accordance with predetermined imaging protocols, and a radio frequency field causes motion of molecules of the gyro magnetic materials. Signals resulting from realignment of the molecules are then detected and processed to reconstruct useful images of the subject. MRI magnet designs include closed magnets and open magnets.
Closed magnets typically have a single, tubular-shaped bore in which the subject, typically a patient in a medical context, may be positioned for imaging. Open magnet designs, including “C” or “U” shaped magnets, typically employ two magnet assemblies separated by a space from one another, with the space between the magnet assemblies defining an imaging volume. The patient is positioned in the imaging volume for imaging. In open MRI systems, the space between the magnet assemblies aids certain patients in remaining comfortable during examinations as opposed to closed or tubular magnet designs. The magnet assemblies, that are positioned apart, also allow for access by medical personnel for surgery or any other medical procedure during magnetic resonance imaging.
In these open MRI systems, permanent magnets are directly attached to a support structure. In currently employed MRI systems, the support structure is made by hot rolling, forging or casting along with extensive machining processes. Excess material is generally removed by such machining processes. In current designs, a substantial volume of material is removed in this manner, with thicker sections being left towards a rear edge and thinner sections being formed near front, typically cantilevered areas. Effective material usage in typical current designs is about 60-65%. Thus the current designs increase material costs due to raw material used as well as the material removed. The current designs also increase manufacturing costs due to the machining processes.
Thus, there exists a need for improved designs for the support structure of open MRI system magnets, and corresponding manufacturing processes, which can reduce costs, while providing high quality and uniform fields needed for imaging.